Molecular mechanism of the role of carbamyl erythropoietin in treating diabetic retinopathy rats

The aim of the present study was to investigate the therapeutic effects of carbamyl erythropoietin (CEPO) and safflor yellow (SY) in the treatment of rats with diabetic retinopathy (DR) as well as exploring the mechanism of action. Male SD rats were used to establish a diabetes model and streptozotocin-induced retinopathy was also performed in rats. A total of 126 rats with DR were obtained, and model rats were randomly divided into the model (n=42), experimental (n=42) and control (n=42) groups. The rats in the model group were injected with saline, the rats in the experimental group were treated with CEPO, and the rats in the control group were treated with SY. After treatment for 2 weeks, the retinas were harvested for quantitative analysis of the mRNA expression levels of angiogenesis-promoting and -inhibiting molecules, apoptosis-promoting and -inhibiting molecules, and oxidative stress pathway-related factors by Reverse transcription-quantitative PCR (RT-qPCR). No significant differences in expression levels of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), angiopoietin (Ang-1), tissue kallikrein (TKLK) and pigment epithelium-derived factor (PEDF) were observed between the experimental and model groups (P>0.05). The expression levels of apoptosis-promoting molecules Bcl-2 related X protein (Bax) and cysteine aspartate specific protease (caspase-3) mRNA in the retina of the experimental group was significantly lower than those in the control group (P<0.05). The expression levels of Bcl-2 and survivin mRNA were significantly higher in the experimental group than in the control group (P<0.05). The expression levels of the oxidative stress pathway nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H quinone dehydrogenase 1 (NQO1) mRNA were significantly higher in the experimental group than in the control group. Therefore, the therapeutic effects of CEPO in treating DR are better than those of SY. As a result, CEPO may inhibit apoptosis and oxidative stress damage of retinal tissue cells in DR rats without affecting angiogenesis.